A common reason for tinnitus is progressive maybe mild hearing loss in both ears over time from noise exposure, age, etc. In that case, the first two treatment options of General Wellness and Hearing aids should be considered. The ATA has a good explanation of how hearing aids can mask the tinnitus, and a list of approved specialists who are not just selling devices from a suitcase.

The definition of a "healthy diet" is completely open, even caffeine and alcohol consumption left to the individual after self-monitoring. I consider LC, which keeps blood glucose low and my weight at a normal BMI, "healthy". No GP or Otolaryngologist at Duke has questioned it, especially since the tinnitus has not become better or worse in 28 years.
Hope it gets better for you!